Preparation

Put oven rack in middle position and preheat oven to 400°F. Put liners in muffin cups.

Whisk together butter, brown sugar, milk, and egg in a bowl until combined well. Whisk together flour, baking powder, cinnamon, and salt in a large bowl. Add milk mixture and stir until just combined. Fold in blueberries gently.

Divide batter among muffin cups and bake until golden brown and a wooden pick inserted into center of a muffin comes out clean, 25 to 30 minutes.